前端运用aJAX调用后端PHP不成功

前端运用aJAX调用后端PHP不成功，总是返回AJAX调用失败

require('./init.php');  
require_once(ROOT_PATH . 'includes/cls_json.php');  

$json = new JSON;  

$action = isset($_REQUEST['action']) ? $_REQUEST['action'] : '';  
if (empty($_REQUEST['action']))  
{  
    $results = array('result'=>'false', 'data'=>'缺少必要的参数');  
    exit($json->encode($results));  
}  
switch ($action) {  
    case 'user_login':{  
        $data = file_get_contents("php://input");  
        $post = json_decode($data,true);  
        $mobile_phone = $post['mobile'];  
        $user_pass = $post['password'];  
        $sql = "select password,mobile_phone from jindong_users where mobile_phone='$mobile_phone'";  
        $row = $db->query($sql);  
        if($rows = $db->fetch_array($row)){  
            if($rows['password']==md5($user_pass)){  
                $res['code']='200';  
                $res['data']='登录成功';  
            }else{  
                $res['code']='402';  
                $res['data']='密码错误';  
            }  
        }else{  
            $res['code']='403';  
            $res['data']='用户名不存在';  
        }  

        exit($json->encode($res));  
    }  

}

前端代码：```javascript

mui.ajax('http://localhost:9096/ecshop_ghuog/api/user.php?action=user_login',{  
                    data:{  
                        mobile:username.value,  
                        password:password.value,  
                        uuid:uuid  
                    },  
                    dataType:'json',  
                    type:'POST',  
                    timeout:100000,  
                    success:function(data){  
                        //{"reslut":1}  
                        if(data.code==200){  
                            //登录成功  
                            plus.ui.toast('登录成功');  
                            plus.storage.setItem("token",data.token);                     
                            mui.openWindow({  
                                url:'personer.html',  
                                id:'list'  
                            })  
                        }else if(data.code==402){  
                            //登录失败  
                            plus.ui.toast('密码错误');  
                        }else if(data.code==403){  
                            //登录失败  
                            plus.ui.toast('账号错误');  
                        }  
                    },  
                    error:function(){  
                        plus.ui.toast('21121');  
                    }